Timing angle indicator for automotive engine distributors



M. J. zlRlN 2,611,837

TINI-NO ANGLE INDICATOR TOR AUTOMOTIVE ENGINE DISTRIBUTORS sept. 23, 1952 Filed July 17, 1951 ATTORNEY m Zw. JT N m L mm M M Patented Sept. Z3, 1952 UNITEDy STATES mrrairll 'oFElCBf ron AUTOMO- TIVE ENGINE DISTRIBUTORS Maxwell J. Zirin, Long Island City, N. Y. Application July 17, 1951, Serial No. 237,113

` io claims. (ci. zoo-19) This inventionrelates to distributors/.for multicylinder automotive engines, and isparticularly directed to distributors, inv conjunction `with which Aan automatic centrifugalV governor-controlled, or an automatic engine vacuum-controlled device,or'both`, are provided to'advance and retard'the timing vof the ignition, by adjustingI the angular position'of'the plate v-ori Vwhich the breaker points are mounted, in accordance with the engine speed, and the load under which it is operating.

The adjustment and setting of the breaker point support-plate, relative to the central cam, mounted on the distributor shaft, in order to obtain the proper spark advance for the requirements of maximum engine performance, normally require a high degree of skill on the part of the person making the adjustment, and usually require special instruments and equipmentto determine the adjusted position.

In order to make the adjustments, i-t is necessary to remove the distributor cap from the case, when renders the distributor inoperative for the period duringwhich the adjustments are made. To enable a person of ordinary skill to check the angular position of the breaker point'support plate, while the engine and distributor are in Operation, I have provided an indicator mechanism which is incorporated'iin the distributor, to enable an operator gular position of the breaker point support plate, relative to either the distributor cap, or the case in which the distributor is mounted, so that the required angular adjustment'can be gaged while the engine is in operation. e Y

This enables the operator to remove the dis- -tributor cap, make the necessary angular breaker point support plate adjustments, after which the cap may be replaced and the adjusted position rechecked on the indicator, when the engine is again-placed in operation. A' l f The 'object of my inventionis to provide ay timing angle indicator, Which may be incorporated in the conventional type of' automotive engine distributor, to enable a person of ordinaryskill to observe the angular position ofthe breaker poin-t support plate, and therefore the degree of spark advance, while the engine-is in operation. A further object i's-to-provide' atimingv indicator on the conventional type .of distributor, which will enable the distributor 'to operate in its normal manner. Y Y

. Another object isto provide a graduated indi-i cator window in the distributor cap, or case, tor' gether with'an indicating device, which can be fto readily observe'the an- I produced at relatively low cost, and installed and adjusted by persons of ordinary skill. j Y

A further object is to provide an indicating device, which can be incorporated in a' wide range of distributor typesand sizes, the'` essential lfea'-l tures of the indicator :being thesame.

A primary Objectis to provide an indicating device, which is adaptable in its construction so that, yit can be mounted in the proper angular position, relative to the cap or case, without'interiering with the operation of other parts ofthe distributor.

Another object is to provide an indicating device which can be used in conjunctionL with a distributor, fitted with a vacuum-controlled or governor-controlled automatic spark advance unit, or both, or other similar type of sparkedvance control unit, without interfering with the operation of the automatic spark positionv con-4. trol, after the initial adjustment and setting-is made. i The accompanying drawings,- illustrative of' one embodiment of my invention, and several modications thereof, together with the description of their construction and the method of installation, operation, and adjustment thereof, will serve to clarify further objects and advantages Vof my invention. j

In the drawingsz- 1: Fig. 1 represents .a front elevation, V,partly broken away, of a distributor assembly `withza window insert mounted in the cap.

' port pla-te Fig. 2 is aplan' view of the'distributor case assembly, shown in Fig. 1, with the cap removed.

Fig. 3 is a section throughv the cap and the window insert of Fig. 1,!taken at 3 3, Fig. 1.

Fig. 4 is a vertical section through the window and a modification of the pointer, shown in Fig. 1, taken at 4 4, Fig. 1.

Fig. 5 is a front elevation, partly broken away,

of a modification ofthe distributor, shownL in Fig. 1, with the window insert mountedin the case.

Fig. 6l is a plan view of the breaker point supand the case, shown in Fig. 5, showing the pointer attached to the plate.v e

Fig. 7 is a front elevation of a portion 'oiga modication of the distributor cap, shown in Fig. l. "1

Fig. 8 is a sec-tion through the distributor cap ofFig. '7, and a'partial plan viewof thel breaker point `support plate, with an indicator segment attached thereto. f-

It wm be understood that the fouewingdescription of the construction and operation oi'Y material, may be removably tted to the open plurality o f latches beingv pril-f end of the case, a vided lto retain the cap on the case; A distributor shaft l2 may be rotatably mounted in the center cf the case-,'-as'indicatedV in Fig. 2, the shaft being generally-drivennat one-half engine speed by a gear train driven by the engine crankshaft, in the usual four-strokecvcle engine.

Y A cam 114;? may befmountedl on the distributor shaft, to openfand'sclo'se.therbreakeripoints, when 'eaeh cylinder freach'es f its." iiririg i: position, Ythe num-ber@ of' lobes.r on. -the-foam :corresponding .with the -number off. engineicylindersil A substantiallycircular'platet5; madeiofmetal, a-plasticlmaterial?, volea combination thereof; may be mounted: in the -.case;1:aro.u1rdxthe:distributor shaftfrthe plate supportingthe breakerfpoints: ITG andfll The relatively? xed brea'keri'pcint it', may be adjustably mounted on the plate bya bracket, anad-iustingscrew4 isgbeing provided-amenable ther relatively: xed vbreaker point ,to be movedyto adjs'tthe. gap formed zina the open. position bei-- tweerrthelxed andthe movable: breaker-points; Their-movable breaker pointv il, may #be attachedl'to 'the' plate; by ai pivoted arm il Y5*, 1 oneA end otwhiehislatta'clred tdthetplate, Vwith the breaker pointnounted atthe` opposite end int axial alignment with the xed breaker point.

The breaker point arm is moved into the open positiorrrby'a cam .followerszZlL attached: tothe ann;'which engages'ftheelobesz of. the cam: to open anclosethe movable-'breaker point; f The .angu- Ianrpostio'n Inf. 'the cam follower .28', A controlling the movement of'tliebreakerlpoint 11;, relative to the cam, which controls the angular pcsitioncef the engine crankshaft, at WhichAfthe: mixture in thaxcylindersaignited; isf-adjusted-'by angularly r moving the breaker: point support; plate -l 5-about the shaft. I Y In nrostfdistributorsi-nuse at the presentrtime, automatic means are provided, either' Within the distributor'or connected thereto, for angularly movingthebreakerpoint supportV plate to' ad- Vance or: retard: the'. spark, cri-ordinated with the engine speed'and' the: load imposed on it,

For advancing the sparkwith...increases 1 in engine' speed, a centrifugal for^other-suitable type of governor may :be mounted *wi-thin the distributor case,- under the :plate l5, the governor being connected to the plate to adjust the angular plate position-,2: .thereby advancing or retarding y"the point, `of ignition' in .co-ordination withanincrease or decrease in .engine speed. .In an engine inwhichfthe crankshaft is rotated in the normal direction, the distributor plate is moved'- clockwisel to retard the point of ignition, and counterclock` wisetoiadv'ance" it. Iii-:orden to compensate for'variations in engine loadfa vacuumA` operated 'unit V`2 I', as; indicated in Fig. 2, may be provided to supplement Vthergovernonltoretardthe: spark vwhen ythefengine load is increased, and advance-it-whenthe -load is decreased, the unit being controlled by the vacuum created in the intake manifold. A connecting arm 22, or other suitable type of connection, may be provided between the vacuum unit and the breaker point plate, the opposite end of the arm being pivotally attached to the breaker point plate, or a bracket, attached thereto, by a rivet 23, a screw, or other suitable attaching means, to adjust the angular position of theiplate under control of ythe '-vacuum" formed in 'the intake v manifold.

In order to observe the angular position of the breakerlpoint-support plate l5, relative to the casera'wndow 25, of arcuate contour, conforming to the contour of the outer wall of the cap Il, may bemolded into, or otherwise supported irranpenng-fcrmed in the outer wall of the cap, as indicated in Figs. l and 3. The window may'bemade of glass, a transparent plastic material, or other similar transparent material.

Afborden 16, 1, ofincreased -wallthicknesxfmay bedormedf integral with the vertica-lJwalLofV the. capi; a painol framesangea l: and 23, -formed integralwith thai-nner. and outerfaces ofthe-wall border.4 respectivelyfformingz-.a .pair of. frames; which` support the., window molded-in place/between the-flanges, the-mannerindicated-m-Figs. l and3.-V Y v In place 'of the forWar-d-.frame ilanges 28 ,.shown' in Figr, a detachable-:'rectangular'.frame-may be substituted, the frame being attached tothe wallborderbya plurality ot screws, orlotheresuitable attaching means, f tofvretain' the windowvin place.:

Al pluralityci equally-spaced angularxgraduaztions 25h-mayr ,be-engravedpr otherwise inscribed onthe outersurface of, thewindow 25, toindicate the angular positionfofafpointer 33,'--which-maybe: attached-to the outer circumference of the breaker point support; plate l5.

TheA pointerV 30, shown, in. 'Figsfl andfL'may be made lof thin. sheet metal, with. a narrow-Vertical section, .tapered atvfthertopgwitli a, Vflange 35, formedA substantially perpendicular to .the Aplane of the vertical sectionof thepointer, andiintegral therewith, mounted` onthe'upper or lower surface of. thebreakerpointplate.r A plurality. of-screws 36, passing through openingsformed in theiiange and. threadably inserted. in the. plate, or frivets, or other. suitable.attaching-means,Ymay be yutilized to. attach ,.the, poi-ntenilange to vthe plate. l.

The .tapered upper tip 31,. of. the vertical section of thepointer, showninigs. land 4, .ma-y be benty outward substantially lparallel to the` lower portion thereof, to movethe pointer closer to the. inner surface. otthewindow, inthe manner indicated in Fig. 4

In-a modification of the-pointer construction, the'pointer 36 may be made-inY the form of a T-section, with` a narrow-verticalsection, tapered at the top, and a cross-bar, integral with and perpendicular to theverticalsection. A plurality of. openings may be formed-through the cross-bar,

, Infplace 'of the screws, may` beA imbedded` in 'aslot bar being molded/'in placa.

The graduations may be spaced. to;;n'dicate crankshaft degrees of advance-in theposition of the engi-ne, ring,;relativeto Vthe top dead center posi-tion;T orftheyjmayl bei spaced in. degrees of 5. angularA rotation of the :breaker point support plateprelative tothe distributor cap,` from'which the :angle ofispark advance is determined.

- :Infour-stroke cycle engines, with the distributor shaft rotated at one-half engine speed, Aone degree of plate movement would be equal to two degrees of spark advance on the crankshaft, so that the lactual spacing of the graduations would have little, if any effect on the operation of the unit.

The central window graduation may be marked 0, or other suitable designation to indicate the normal spark advancewhen the engine is operated, before the breaker point plate is angularly adjusted by either the centrifugal governor, or the vacuum-controlled unit, hereinbefore referred to, or itmay indicate the tcp dead center, of the piston, depending upon the rangev of the graduations, and the normal spark advance forwhich a particular engine is designated.

f rvNumerals 38 designating degrees of crankshaft angularr position would be engraved, or otherwise indicated on the other graduations,

In operation of the unit, the engine is operated in the normal manner, with the distributor cap in the closed angular positionof the pointer may be checked against the graduations formed on the window 25. The engine would be operated at various speeds and under varying load conditions, the

position, shown in Fig. 1. The

operator observing the' changes in angular position of the contact support plate, as indicated by the window graduations 29.

- In this manner, he is enabled to determine whether the breaker point plate is adjusted to the normal angle of spark advance for which the engine is designed, and can also gage from the changes in plate position caused by the centrifugal-governor, which moves itin accordance with variations in engine speed, the vacuum controlled unit, which adjusts it in accordance with the manifold vacuum, which varies with the engine yload conditions, or other type of automatic control mechanism for adjusting the spark timing position, thus enablingthe operator to determine whether the governor, or the vacuum control unit, or both, are functioning properly.

After the various plate angle observations are made by the operator, he can shut oif the engine, remove the distributor cap, and adjust the angular position of the breaker point support plate, by observing the pointer 30, and making any repairs or adjustments required on the governor, or the vacuum controlled unit, after which the engine may be startedagain, and the angular position of the plate, as-indicated by the position of the pointer against the window graduations, rechecked in the manner hereinbefore described.

Figs. 5 and 6 show a modification ofthe distributor construction, shown in Figs. l and 2. In place-of the window 25, mounted in the cap, a similar window 4| may be mounted in the vertical wall of the case IB. A heavy border 42, may beformed integral with the vertlcalwall of the case, a pair-of-fianges 4 3, formedintegral-with the inner and outer-faces of thev wall' border, forming a pair of frames, whichsupport the window 4|, in arnanner similar to that shownk in section'in Figs- 3 and 4. The window 4| may be molded in place in the case, inthemann'er shown in Figs. 3v and 5, or aseparate forward frame,re movably attached'to the wall border, may be substituted for the forward 'integral frame, to removably support the window 4|. A' plurality'of equally-spaced angular graduaf and hereinbefore tions 44 may be inscribed on the outer surface of the window 4|, in a manner similar to those shown in Fig. 1,` the graduations being. directed downward to indicate` the angularv position of a pointer 45, which may be attached to the breaker point supportl plate |5, in the manner indicated in Fig. 5.- The pointer 45 may be constructed and attached to the breaker point plate in the manner shown in Fig. 5, with the tapered tip 46, of the vertical section 41 of the pointer, directed downward in substantial alignment with the position, of the graduations 44, as indicated in Fig. 5. f

The pointer 45, which is generally similar in construction, to that shown in Figs. 1 and 4, may be formed with a depending verticalsection, the lower end of which is tapered, and an integral flange, perpendicular to the plane of the vertical-section, formed at the top, as indicated in Fig. 5; The pointer flange may be attached to the plate in the manner shown in Figs. 1 and 4. In the pointer shown in Fig. 5, a flange 49, formed integral with the vertical section, may be mounted on the top or bottom surface of the breaker point support plate. A plurality of screws 55, passing through openings formed in the ange 49, and threadably inserted in the plate, or a plurality of rivets, passing through the iiange and the plate, or other suitable attaching means, may be utilized to attach the pointer flange to the plate, in the manner indicated in Figs. 5 and 6, or Fig. 4. The pointer 45 may be attached to the plate by means of the iiange 49, or thepointer iiange 49 may be molded directlyinto the plate, adjacent the outer circumference thereof. The depending tip 46, of the vertical section of the pointer 45, may be in substantial alignment with the vertical section of the pointer, or the tapered lower tip 46, of the vertical section may be bent outward, in the manner indicated in Fig. 4, to bring it closer to the inner surface of the window. The operation of the unit, shown in Fig; 5, is substantially the same as that shown in Fig. 1, described, except that the angular position of the breaker point support plate |5 may be gaged through the window 4|, supported in the case, by observing the position of the tapered tip, of the depending vertical section of the pointer against the graduations 44, inscribed on the surface of the window.

The only difference in the operation and adjustment of the distributor shown in Fig. 5, over that shown in Fig. 1 is the fact that after the angular position of the pointer 45, relative to the window graduations, isobserved through the window 4|, under various engine operating conditions of both speed and load. The angular position of the breaker point support plate may be adjusted by observing the position of the pointer against the graduations, through the window 4|, after the cap is removed, and while the adjustments are being made. f

In another modification/of the construction',-

shown in Figs. '7 and 8, a window 52, similar to that shown in Fig. l, may be mounted in the cap Il, in substantially the same manner.u In` stead of` the graduations 29, shown in Fig. 1, a single` hairline v53, may be inscribed fin the center of the outer surface of the window 52.v .Y

i Ari-angle indicator segment 54, of arcuate contour, substantiallyparallel to the window 52, may be attached to the uppersurface of the breaker point plate, a ange 55, substantially perpendiculanto and. integral: Withl'the. segment. 541- being attached toltlie plate by a pluralityofrrvetsv B', screws; 'fori4 othersuita'ble attaching. means.;

A` plurality vof equally-spaced anglegraduations-'51; similartothose shown. in Fig. '1, may be engraved orotherwise inscribed on the surface of thesegmentd, in` aligrnnentwiththe. window. The position ofthe angle graduationsY 5.7` on the segment 54', relative to the hairline 53, inscribed andthe window, indicates the angular'positio'n of the breakerv point support plate, in the same manner as the pointer 3,shown in Fig. 1,..and hereinbefore described. The operation ofk the unit,` shown in Figs.v 7 and 8, andthe vadjust-- ment thereof,'is substantially theY same asi that shown' in Fig. 1, and' hereinbefore described;

Inv place* of theA construction, showninliig.` 1, tHe ventire cap Il may be molded of a .transpar ent plastic material', or other suitable transparent material, havingV the necessary heat-resistant and electrical non-conductive characteristics. The graduations 2S formed on the. window 25, shown in Fig. l, may be engraved, or otherwise inscribed directly on the surface of' theouter'wa'll of thetransparent case, insub'stantially the' same relativelposition.

The-pointerr' and the method' of attaching the pointerV to the breaker point support plate Would be substantially the same as that shown in Figs. land 4 and hereinbefore described.

The operation of a unit of this type would be substantially the same as that shown in Fig. i, the angular position of thebreakerpointsupport plate being gaged` byobservingthe angular po'sition'of` the pointer against the graduations inscribed on-the outer wall of the transparent casez In Aplace of the construction shown 'in Fig. 5, the entire case 9U may be molded entirely of the-same type of transparent plastic material, theA graduations lili,l inscribed on the Window 4|, shown in Fig. 5,V being formed directly on the outer Wall of the case, thus eliminating` the Window 4|.

The pointer' 45, formed with a depending vertical section, would be substantially the same asthat shown in Fig; 5, the pointer vbeing attached to the breaker 'point support plate inthe same manner.

The operation of the' unit would' be substantially the same as that shown in Fig. 5, and hereinbefore described. Y The angular position of' the breaker point support plate being gage'd by observing the taperedtipl of the depending vertical section 'of the pointer through the transparent outerv Wall of the case, against the graduations inscribed on the outer Wall of the case.

It will be apparent to those skilled in the art that my present inventionis not limited to the 'specic details described above and shown in th'e drawings, and thatV various further modiiic'ationsare possible in carrying out the features of' .the invention and the construction', adjustment and utilization thereof, Without departing from the spirit and scope of the appended claims.

What I claim is;

l. In an internal combustion engine ignition distributor, mountedl Within a case, with a cap removably mounted on the case, a rotatable shaft supportedV Within the case, a plate surrounding the shaft, and a setl of ybreaker points supported by said plate, and means mounted on said shaft, controlling one of the breaker points, the combination of a transparent .Window` mounted in saidpap', means attached to the breaker point support plate indicatingzthe angular-.positionnf the plate relative to thescanand. means formed on said Window, indicatingthe angular move'k ment ofisaid':indicating.` means, while:the1distributor'lcap isclosed.v

2. Inan 'internal combustionengine ignition distributor, mountedwithin a hollow case, with` a cap removably mounted` on the casel a shaft. rota'tablyv supported Awithin .the case, aplate surrounding the shaft, a plurality of breaker points supported by said plate, and meanslmounted on saidY shaft' controlling one VsetV oi the breaker pointsgthe combination ofa transparent window molded into thev outer' Wall ofk said cap, means attached Ito the breaker: pointl support. plate;v indioating. the. angular .position -or the'. plateY relaitiveitorthel capi-and means formed on said' .winev dow indicating. the variationslin'anglilar. position of said indicating. means;

3. In: an. internal combustion` enginezignition distributor mounted Withinia hollow,:substan tially cylindrical'..cas`e,- WithV a cap.. removably mounted on thefcase,.a shaft 4rotatably supported within *theY case; a plate.` surroundingy the'. shaft, a setvof breaker points supported by-v said plate, and a-cam mounted on saidl shaft, controlling one of .said breaker points, the .outer wall of-said cap having an .opening formedl therethrough, the combinationfofi a transparent window attached to Sthe wall of the cap'in alignmentwith Vsaid opening, an 'indicating device attachedto the breaker point' support` plate, 1 normally visible through said Window, said window havingv a pluralityU of angular graduations inscribed "thereon,

' I said graduations' indicating the' angular movement of theplate indicating device, while the distributor: vcap is mounted on'the case! 4. In an internal combustionengine ignition distributor, mounted :withina holloW,-substaln tially cylindrical case, with' a. cap removably mounted on the case, a rotatable shaft supported Within the case, a plate surrounding the shaft, a set of breaker points supported by said plate, and' a cam mounted on said shaft, controlling oneof said. breaker points, vthe outer wall of said case having an opening formed therethrough, the combination of a `transparent window attached to the Wall of the case irl-alignment with said opening, a pointer, attached to the breaker point support plate, normally visible through the window, said Window having a plurality of angular graduations inscribed thereon, said graduationsfindicating Ythe angular movement of the plate. relative to the case.

5. In an internal combustion engine ignition distributor, mounted Within a hollow, substantially cylindrical case, with a cap removably mounted on the case, a rotatable shaft supported Within the case, a plate surrounding the shaft, a set of breaker points a cam mounted 0n said shaft, controlling one of said breaker points, the outer Wall of said cap having an" opening formed therethrough, the combination 'of a transparent windowof arcuate contour., attached to the wall of the cap, in align'- mentl with saidf lopening, a pointer, mounted on thebreaker point support plate, normally visible through the window,v means Aattaching said pointer to the.-plate,said Window having ya plurality oifangular 'graduations inscribed thereon, said' graduations indicating Athe angular .movement of thev pointer and the plate; while the `cap is in thei'closed position;`

6. In an internal' combustion'fengine' ignition distributor, mountedy withina hollow, substansupported by said plate, and

mounted on the case, a rotatable shaft supported Within the case, a plate surrounding the shaft, a set of breaker points supported by said plate, a cam mounted'on said shaft, controlling one of said breaker points, and means attached to said breaker point support plate, automatically rotating said plate to adjust the spark timing coordinated with variations in the engine speed and load, the outer wall of said cap having an opening formed therethrough, the combination of a transparent Window of arcuate contour, attached to the Wall of the cap, in alignment with said opening, a pointer, mounted on the breaker point support plate, normally Visible through the window, said pointer comprising a vertical section, with a flange substantially perpendicular to the Vertical section, means attaching the pointer flange to the plate, said window having a plurality of angular graduations inscribed thereon, co-ordinated with the pointer, said Window having designations formed thereon, in alignment With the graduations, indicating the angular position of the graduations relative to a datum graduation, said graduations indicating the angular movement of the pointer and the plate, While the cap is in the closed position.

7. In an internal combustion engine ignition distributor, mounted Within a hollow substantially cylindrical case, with a cap removably mounted on the case, a shaft rotatably supported Within the case, a plate surrounding the shaft, a set of breaker points supported by said plate, a cam, mounted on said shaft, controlling one of said breaker points, and means attached t said breaker point support plate, automatically rotating said plate to adjust the spark timing coordinated With variations in the engine speed and load, the outer Wall of said case having an opening formed therethrough, the combination of a transparent window attached to the Wall of of the case in alignment with said opening, a pointer, mounted on the breaker point support plate, normally visible through the Window, said pointer comprising a vertical section, with a iiange substantially perpendicular to the Vertical section, to the plate, said window having a plurality of angular graduations inscribed thereon, coordinated with the pointer, said Window having designations formed thereon, in alignment with the graduations, indicating the angular position of the graduations relative to a datum graduation, said graduations indicating the angular movement of the plate, relative to the case.

8. In an internal combustion engine ignition distributor, mounted Within a hollow substantially cylindrical case, with a cap removably mounted on the case, a shaft rotatablysupported by the acse, a plate surrounding the shaft, a set of breaker points supported by said plate, a `cam mounted on said shaft, controlling one of said breaker points, and means attached to said breaker point support plate, automatically rotating said plate to adjust the spark timing, coordinated With variations in the engine speed and load, the outer Wall of said cap having on opening formed therethrough, the combination of a transparent Window supported by the Wall of the cap, in alignment with said opening, an arcuate indicator segment mounted on the breaker point support plate, in substantial normal alignment means attaching the pointer flange 1 the window, a flange, integral with with the Window, said segment having a plurality of angular graduations formed thereon, and means formed on said window, (io-ordinated with the angular graduations, indicating the angular position of the plate relative to the cap, while the cap is in the closed position.

9. In an internal combustion engine ignition distributor, mounted Within a hollow, substantially cylindrical case, with a cap removably mounted on the case, a shaft rotatably supported by the case, a plate surrounding the shaft, a set of breaker points supported by said plate, a cam mounted on said shaft, controlling one of said breaker points, and means, attached to said breaker point support plate, automatically rotating said plate to adjust the spark timing, coordinated With variations in the engine speed and load, the outer Wall of said cap having an opening formed therethrough, the combination of a transparent window molded into the wall of the cap, in alignment with said opening, an arcuate segment mounted on the breaker point support plate in substantial normal alignment with the window, and means attaching said segment to the plate, said segment having a plurality of angular graduations formed thereon, said Window having a hairline inscribed thereon, located in co-ordination with said graduations, said gradnations indicating the angular movement of the piate relative to the Window hairline, while the cap is in the closed position.

l). in an internal combustion engine ignition distributor, mounted within a hollow, substantially cylindrical case, with a cap removably mounted on the case, a shaft rotatably supported by the case, a plate surrounding the shaft, a set of breaker points supported by said plate, a cam mounted on said shaft, controlling one of said breaker points, and means attached to said breaker point support plate, automatically rotating said plate to adjust the spark timing, coordinated vvith variations in the engine speed and load, the outer Wall of said cap having an opening formed therethrough, the combination of a transparent Window supported by the wall of the cap, in alignment with said opening, an arcuate segment mounted on the breaker point support plate in substantial normal alignment with said segment, mounted on the plate, and means attaching said iiange to the plate, said segment having a plurality of angular graduations formed thereon, said segment having designations formed thereon, in substantial alignment with the graduations. indicating the angular position of the graduations relative to 'a datum graduation, said window having a hairline inscribed thereon, located in co-ordination with said graduations, said graduations indicating the angular movement of the plate relative to the window hairline, While the cap is mounted on the case.

MAXWELL J. ZIRIN.

REFERENCES CITED The following references are of record in the i'ile of this patent:

vUNTED STATES PATENTS 

